Electrochemical measuring systems, e.g., sensors, are used customarily, for example, to determine a pH value of a liquid medium or also to determine a carbon dioxide concentration of a medium. Measuring systems configured for such purposes include potentiometric electrodes that may be configured in a variety of manners. To determine a pH, for example, a pH-sensitive glass electrode and a reference electrode are used. To determine a carbon dioxide concentration, for example, a platinum electrode is used in combination with a silver reference electrode.
Potentiometric electrodes are classified as ion electrodes or redox electrodes. Ion electrodes are in turn classified as type 1 ion electrodes or type 2 ion electrodes. In the case of a type 1 ion electrode, the metal making up the electrode is submerged into a solution of its own salt. An electrode of this type is, for example, an Ag/AgNO3 electrode. In the case of an ion electrode of the second type, a metal coated with a poorly soluble metal salt is submerged into an aqueous solution containing a readily soluble, chemically inert salt including the same anion as the metal salt.
A redox electrode is made up of a neutral working electrode, which is made, for example, of platinum, and a solution containing a corresponding redox pair.
An electrode of the second type is used, for example, as a reference electrode, because it allows uncomplicated handling when the potential signal is constant.
To develop an electrochemical measuring system including one electrode, various materials are tested individually and in succession in relation to a suitable reference electrode for the selection of the electrode material. This method for selecting an electrode material has the disadvantage of being very time-consuming.